1. Field of the Invention
This invention relates to a flat panel display device, and more particularly to a method of driving a plasma display panel(PDP) for displaying a picture and an apparatus thereof.
2. Description of the Related Art
Nowadays, there have been actively developed a flat panel display device such as a liquid crystal display(LCD) device, a field emission display device, a plasma display device and so on. The flat panel display device displaying a picture making use of a discharge has been highlighted due to its simple structure and the easiness in manufacturing it. Also, the plasma display device provides a high brightness, a high radiation efficiency, an improved memory ability and a wide view angle of more than 16xc2x0. Furthermore, the plasma display device has an advantage in that it can implement a large screen of more than 40 inches. Such a plasma display device is classified into a direct current(DC) system and an alternating current(AC) system depending on a discharge generation type. The alternating current system of plasma display device has been noticed because a consumption power is low and a lifetime is long compared with the direct current system.
Since the plasma display device has a characteristic in that its brightness becomes different in accordance with a discharge time of each cell, it must control a discharge time of each pixel in one field interval(e.g., 16.67 ms in the case of an image signal of NTSC system) of a single image signal so as to display a moving picture having a gray scale. The driving apparatus of AC system displaying a picture depending on the discharge interval includes a plasma display panel(PDP) driving apparatus as shown in FIG. 1. The PDP driving apparatus of FIG. 1 includes a scanning/sustaining electrode driver 2, a common sustaining electrode driver 4 and first and second address electrode drivers 6A and 6B, which are connected to a PDP 8. The PDP 8 is provided with scanning/sustaining electrodes Y1 to Yn and common sustaining electrodes Z1 to Zn which are alternately arranged in the vertical direction, and address electrodes X1 to Xm arranged, in parallel, in the horizontal direction. In the PDP 8, mxn pixels are formed in a matrix pattern in such a manner to be connected to the scanning/sustaining electrodes(Y), the common sustaining electrodes(Z) and the address electrodes (X). The scanning/sustaining electrode driver 2 allows pixels to be discharged to be sequentially selected in the line unit and a discharge in each of the mxn pixels to be sustained. To this end, as shown in FIG. 2, the scanning/sustaining electrode driver 2 performs a reset operation for make a uniformity of the cells by a writing and erasing operation on the entire cells, an addressing operation of allowing the pixels to selectively initiate a discharge, and a sustaining operation of allowing a discharge of the pixels to be sustained. The scanning/sustaining electrode driver 2 applies writing and erasing pulses to the scanning/sustaining electrodes Y1 to Yn in a reset interval, applies a scanning pulse to the scanning/sustaining electrodes Y1 to Yn sequentially in an addressing interval, and applies a sustaining pulse to the scanning/sustaining electrodes Y1 to Yn in a sustaining interval. Also, the scanning/sustaining electrode driver 2 may additionally supplies a writing pulse to the scanning/sustaining electrodes Y1 to Yn in the reset interval to form a wall charge at each of the mxn pixels. The common sustaining electrode driver 4 applies a predetermined level of voltage signal to all the common sustaining electrodes Z1 to Zn. The first and second address electrode drivers 6A and 6B supply an image data to the address electrodes X1 to Xm in the PDP 8 in such a manner that the image data is synchronized with the scanning pulse. The first address electrode driver 6A supplies an image data to odd-numbered address electrodes X1, X3, . . . , Xm-3, Xm-1 while the second address electrode driver 6B supplies an image data to even-numbered address electrodes X2, X4, . . . , Xm-2, Xm.
Further, the plasma display device controls a light quantity depending on the discharge time to realize a gray level. In other words, in the plasma display device, the discharge time is controlled such that a contrast and a chromaticity of the picture become different. To this end, as the plasma display device of AC system is used a PDP driving technique of address display separated (ADS) system. In this PDP driving technique of ADS system, a single field is divided into a number of sub-fields in accordance with a gray level intended to be implemented, and each sub-field is divided into an addressing interval and a sustaining interval to drive the PDP 8. For instance, when it is intended to realize 256 gray levels, a field interval corresponding to {fraction (1/60)} second is divided into 8 sub-fields SF1 to SF8 as shown in FIG. 3. Also, each of the 8 sub-fields SF1 to SF8 is again divided into an addressing interval and a sustaining interval. Each of pixels selected in the addressing interval indicated by oblique lines in FIG. 3 initiates a discharge. The discharge initiated at each of the selected pixels is sustained in a sustaining interval. The sustaining interval is lengthened by a interval corresponding to 2n depending on a weighting value of each sub-field. In other words, the sustaining interval involved in each of first to eighth sub-fields increases at a ratio of 20, 21, 23, 24, 25, 26 and 27. To this end, the number of sustaining pulses generated in the sustaining interval also increases into 20, 21, 23, 24, 25, 26 and 27in accordance with the sub-fields. A brightness and a chrominance in each pixel are determined in accordance with a combination of the sub-fields SF1 to SF8.
In such PDP driving method of ADS system, a brightness of each pixel is determined by a sustaining interval. In other words, since the sustaining interval becomes more decreased as the address interval increases, a maximum value of the brightness displayed on the screen is lowered. For instance, it is assumed that one field interval of 16.67 ms is divided into 8 sub-fields(i.e., upon implementation of 256 gray scales) and a time of 3.6 xcexcs is required to address a single pixel line. Also, assuming that 480 pixel lines has been formed in the PDP, when the scanning/sustaining electrodes Y1 to Yn are driven with a single scanning/sustaining driver 2 to scan a screen, a time of xe2x80x9c480xc3x973 xcexcs=1.44 xcexcsxe2x80x9d is required to scan the entire 480 lines sequentially for each sub-field, and an addressing interval of 1.44 xcexcsxc3x978=11.52 xcexcs is required for each field interval. In other words, an addressing interval of 11.52 xcexcs is required to scan 480 pixel lines during one field. Accordingly, only 5.15 ms equal to 30% of 16.67 ms which is a time assigned to one field, is assigned to the sustaining interval. Also, since a reset interval for allowing all the cells to be in the same state by eliminating an affect of previous discharge at the inner side of the cell every sub-field must be included, the sustaining interval is shortened into, for example, 20 to 25%. Furthermore, since the number of pixel lines becomes more increased as a resolution of the PDP is heightened, the sustaining interval is more shortened. Also, the sustaining interval is more and more shortened as the PDP has a larger scale screen. Due to this, the conventional PDP driving method fails to brighten a screen into more than the limit. In addition, the conventional PDP driving method can assure the brightness of screen sufficiently as a resolution of the PDP becomes high or a screen of the PDP becomes large.
Accordingly, it is an object of the present invention to provide a plasma display panel driving method and apparatus that can improve the brightness of screen into more than the limit.
In order to achieve these and other objects of the invention, a plasma display panel driving apparatus according to one aspect of the present invention includes a plurality of cells formed by a plurality of electrode lines defined on a substrate in a matrix type, the electrode lines including scanning and sustaining electrodes for selectively scanning and sustaining said cells for each line; and an electrode driver for driving the scanning and sustaining electrodes with dividing them into more than two.
In a method of driving a plasma display panel according to another aspect of the present invention, scanning and sustaining discharge are driven such that at least one area performing a scanning operation and at least one area performing a sustaining discharge by sequentially scanning a plurality of lines exist within the same plasma panel.